The present invention relates to a display drive control device and a drive method thereof. More specifically, the present invention relates to a display drive control device having a power supply circuit which generates a plurality of voltages from a single main power supply according to a specified procedure.
A display drive control device having a so-called flat panel display device is used as a display device for electronic devices such as personal computers, television sets, cellular phones, and portable information terminals. In particular, liquid crystal displays are extensively used for cellular phones that are remarkably widespread in recent years. An electroluminescence display (organic or inorganic ELD) will be put to practical use in the near future. The following description of the present invention concerns a cellular phone using a TFT (Thin File Transistor) liquid crystal display with respect to its display drive control device (liquid crystal display drive control device) as an example. The description also applies to the other display drive control devices having the power supply circuit to generate a plurality of voltages from the main power supply. For example, the other devices include non-TFT liquid crystal display drive control devices such as the above-mentioned ELD and STN (Super Twisted Nematic), and display drive control devices using field emission displays (FEDs).
For example, a liquid crystal display drive control device requires various levels of voltages to drive its liquid crystal display (also referred to as a liquid crystal display panel or simply as a liquid crystal panel). For this reason, the liquid crystal display drive control device (also referred to as a liquid crystal controller or liquid crystal driver) generally includes a power supply circuit that generates different levels of voltages from a single main power supply.
The display device such as a liquid crystal display needs to start operating with no unwanted image or flicker. For this purpose, it is necessary to generate a plurality of voltages according to a specified sequence with a constant time interval. The sequence and the time are determined by electrical characteristics of the liquid crystal display. This procedure must be always followed when the power supply circuit is used.